It is well known in the art of firearms marksmanship to practice by “dry firing.” This is the actuation of the trigger and firing mechanism without the use of live ammunition. When performed with due care, it is a safe means to gain familiarity and “muscle memory” that improves accuracy at low cost. Products known as “snap caps” are sometimes used to simulate the presence of ammunition and thus avoid any damage to the firearm that might occur. These devices have the approximate external shape of live ammunition and thus may be inserted into the chamber before practicing, but inside contain a small plunger and a spring that absorb the shock of the firing pin as a primer might.
However, firearms users do not always exercise due care. Sometimes live ammunition is placed in the chamber rather than a snap cap. As a result, the firearm may be discharged unintentionally, posing a significant risk of injury or death. In addition, there is no easy way for someone to confirm visually that snap caps are inserted rather than live ammunition. Thus, for instance, while and instructor might wish to have students conduct dry fire drills in a classroom rather than on a firing range, doing so tends to encourage the violation of fundamental safety rules because it involves pulling the trigger of a firearm without a proper bullet-absorbing backstop.
Other forms of practice, such as drawing from a holster or drawing from concealment, are also potentially dangerous if attempted without proper attention to the unloading of the firearm.
Special devices which simulate both the external dimensions of firearms, which are useful for practicing drawing from a holster or conducting retention and takeaway drills with a partner, do exist. In addition, some manufacturers produce devices that simulate both the appearance and the operation of particular firearms, but which do not permit ammunition to be inserted, to allow the experience of dry firing in safety. However, the cost of such dummy guns is often prohibitive for the average person. In some cases the dimensional fidelity of dummy guns can be questionable, which can mean that, for instance, drawing a plastic casting of a gun from a holster can be a very different experience than drawing the real thing, and therefore encourage the development of bad habits. Thus such tools are often limited to law enforcement or military agencies with sufficiently large budgets and competent armory staffs to ensure proper operation and training value.